1. Field of the Invention
The present invention relates generally to the fabrication of magnetic heads for hard disk drives, and more particularly to the fabrication and removal of seed layers utilized for electroplating magnetic head components such as induction coils and magnetic pole tips.
2. Description of the Prior Art
Several components of magnetic heads are typically fabricated utilizing electroplating processes, and a typical initial step in such electroplating processes is the deposition of an electrically conductive seed layer. A patterned photoresist is photolithographically fabricated upon the seed layer and the desired magnetic head component, such as an induction coil or a magnetic pole, is thereafter electroplated upon the seed layer within the patterned photoresist layer. Following the electroplating of the component, the photoresist layer is removed, and it is next necessary to remove the portions of the seed layer that are not covered by the electroplated component. The seed layer removal step is necessary to prevent electrical shorting of the components. In the prior art fabrication processes, an ion milling step or a sputter etching step is utilized to remove the seed layer.
The prior art seed layer removal step creates unwanted problems in magnetic heads. One problem is that portions of the removed seed layer become redeposited along the sides of the electroplated components. These redeposited seed layer portions can subsequently flake off and cause unwanted electrical shorting of the components. Additionally, the ion milling or sputter etching process also removes significant portions of the electroplated components that are exposed to it during the seed layer removal process. Thus, the electroplated components are plated up higher than would otherwise be necessary, such that after the seed layer removal process, the remaining thickness of the component is as desired. To fabricate the components with this additional thickness, the aspect ratio of the photoresist trenches must likewise be increased, and problems associated with the photolithographic fabrication of high aspect ratio trenches are encountered. Additionally, because it is necessary to ensure that the seed layer has been effectively removed from between the electroplated components, significant overetching is typically performed, which exacerbates the problems described hereabove. Additionally, the overetching can damage layers and structures beneath the seed layer.
As described below, the present invention solves these problems by utilizing a seed layer material that is susceptible to a reactive ion etch (RIE) removal process. Utilizing this RIE seed layer removal process, the seed layer redeposition problem is eliminated, the additional thickness of the components is not required because the electroplated components are not substantially attacked by the RIE process, and seed layer overetching is not a problem because layers beneath the seed layer are not affected by the RIE process.
The electroplated components of a magnetic head of the present invention are fabricated utilizing a seed layer that is susceptible to reactive ion etch removal techniques. A preferred seed layer is comprised of tungsten or titanium and it is fabricated in a sputter deposition process. The seed layer is electrically conductive and the electroplated components, such as induction coil members and magnetic poles, are effectively electroplated into photolithographically created photoresist trenches that are fabricated upon the seed layer. Following the electroplating of the components, the photoresist layer is removed utilizing a standard wet chemical process to expose the seed layer. Next, utilizing a fluorine species reactive ion etch process the seed layer is removed, and significantly, the fluorine RIE process creates a gaseous tungsten or titanium fluoride compound removal product. The problem of seed layer redeposition along the sides of the electroplated components is overcome because the gaseous fluoride compound is not redeposited. Additionally, because the fluorine RIE process does not significantly attack the electroplated components, such as copper induction coil members and NiFe magnetic pole members, it is not necessary to electroplate these components to an additional thickness. Thus, the increased aspect ratio photoresist trenches that are problematic in the prior art are not required. Furthermore, overetching is not a problem because the fluorine RIE does not attack layers, such as aluminum oxide insulation layers, located beneath the seed layer.
The present invention also includes an enhanced two part seed layer, where the lower part is tungsten, titanium or tantalum and the upper part is composed of the material that constitutes the component to be electroplated. This two part seed layer is beneficial because a tungsten, titanium or tantalum seed layer (and particularly tantalum) may form an unwanted oxide surface coating which inhibits adhesion and electrical conduction to the electroplated component, and the upper seed layer part prevents the oxide formation.
It is an advantage of the magnetic head of the present invention that seed layer redeposition on the sides of electroplated components is eliminated.
It is another advantage of the magnetic head of the present invention that removal of the seed layer is efficiently accomplished without removal of material from other magnetic head components.
It is a further advantage of the magnetic head of the present invention that induction coil members can be spaced more closely together because seed layer removal between the components is more efficiently accomplished.
It is yet another advantage of the magnetic head of the present invention that induction coil members and magnetic pole members can be more easily fabricated because the aspect ratio of photoresist trenches can be reduced.
It is an advantage of the seed layer removal process of the present invention that it utilizes a reactive ion etch step which removes the seed layer in a gaseous compound.
It is another advantage of the seed layer removal process of the present invention that seed layer redeposition along the side of electroplated components is eliminated.
It is a further advantage of the seed layer removal process of the present invention that material removal of electroplated components does not occur during the seed layer removal process.